Construction of underground tanks for storing liquid fuels and other fluids



Nov. 2, 1943. s. KLINGBERG 2,333,315

CONSTRUCTION OF UNDERGROUND TANKS FOR STORING LIQUID FUELS AND OTHER FLUIDS Filed Aug, 25, 1939 3 Sheets-Sheet 1 Nov. 2, 1943. s KUNGBERG 2,333,315

CONSTRUCTION 0E UNDERGROUND TANKS FOR sToRING LIQUID FUELS AND OTHER ELUIDS Filed Aug. 25, 1939 3 Sheets-Sheet 2 S. KLNGBERG Nov. 2, 1943.

CONSTRUCTION OF UNDERGROUND TANKS FOR STORING LIQUID FUELS AND OTHER FLUIDS Filed Aug. 25, 3.959 C5 Sheets-Sheet 3 Patented Nov. 2, 1943 CONSTRUCTION OF UNDERGROUND V4TANKS FOR STORING LIQUID FUELS AND OTHER FLUIDS Sven Klingberg, Traneberg, near Stockholm,

Sweden, assignor to Svenska Entreprenad Aktiebolaget, Stockholm, Sweden, a corporation of Sweden Application August 25, 1939, Serial No. 291,984 In Sweden September 5, 1938 6 Claims.

For protection against air bombs and artillery fire in war-time, it is desirable to sink the tanks necessary for storing liquid fuels and other fluids, into underground cavities, preferably in rocks. Then the tanks are protected by a layer of rock or the like having a suflicient thickness. Heretofore such underground tanks were erected as free, self-supporting tanks within the underground cavity. Such plants suffer from certain drawbacks and risks, and their costs of erection and maintenance arerelatively high. Thus, in such plants the underground cavity must be considerably larger than the tank itself, because a certain space must be left between the wall of the tank and the wall of the rock, for permitting alterations and repairs of the sheet metal. The sheet metal of the tank walls must be designed to carry the total pressure of the liquid stored, and, especially in high tanks, this renders it necessary to use very thick sheet metal in the lower parts of the tank, and consequently also renders them expensive. The wall of the tank has one single sealing element, viz. the sheet metal, and if a leak occurs in the sheet metal, for instance, if stones fall down from the walls of the rock, the liquid stored flows out into the cavity, which means a certain' loss and, especially in the case of volatile liquids, may involve risks of fire and explosions.

The chief objects of this invention are to overcome such drawbacks and risks and to render it possible to store liquids in underground cavities at lower costs than heretofore. Both the costs of erection and the costs of maintenance of the tanks are reduced in accordance with this invention.

Another object of this invention is to render it possible to build underground tanks of thin sheet metal, filling out the space between the sheet metal and the wall of cavity with liquid-tight concrete, to form protection against external water and to prevent the liquid stored from leaking out, if leaks should occur in the sheet metal. A

Another object of this invention is to render it possible to build the sheet metal walls very close to the wall of the cavity, by building the tank entirely from its inner side.

Another object of this invention is to render scailolds unnecessary, by building the tank from a raft floating in the tank.

Another object of this invention is to render it possible to test the tank successively during its erection by means of the Water serving to lift the raft.

Another object of this invention'is to eliminate tensile stresses in the tank, by cooling the sheet metal during the erection. A

Other objects of this invention will be evident from the following specification and claims.

One embodiment of the invention is illustrated in the annexed drawings.

Fig. 1 shows a vertical section through the tank and the adjacent portions of the rock.

Fig. 2 shows, on a larger scale, a vertical section through a portion of the wall of the rock and the adjacent parts of the tank.

Fig. 3 shows a vertical section on the line III- III in Fig. 2.

Fig. 4 shows, on a larger scale, a vertical section through the rock and the adjacent parts of the tank, the section being taken in a different plane from Fig. 1. l

Fig. 5 shows, on a still larger scale, a vertical section illustrating how the different parts of the tank are joined together.

Fig. 6 shows a part of a tank under construction.

Fig. 7 shows a horizontal section on the line VII- VII in Fig. 4.

Fig. 8 shows a vertical section on the line VIII-VIII in Fig. 7.

Referring now to the drawings, I indicates the side wall and 2 the bottom of the preferably cylindrical shaft blasted into the rock. For v draining the cavity from external water, such as subsoil water, pipes 3 are drilled into the rock in such fissures and cracks, in which water actually ows or may be expected to ow. At the places, where the pipes enter the fissures, and also on the whole surface of the fissure facing the cavity, quick-setting concrete mortar 4 is lled to seal oil the ssures from the cavity. The pipes 3. are connected with vertical pipes 5, which themselves are connected to an annular draining duct 6, located at the bottom of the cavity and being, for instance, made of pipes having open joints. Around duct 6 a block of porous concrete l (that is concrete or cement without any addition of sand) is moulded. At their tops the pipes 5 are connected with a circular duct 25 having an air vent 26 for venting the drainage system.

On the bottom 2 of the cavity a layer 8 of concrete is laid and at the top thereof a layer of sand asphalt 9. On this foundation the bottom plates I0 are laid, which plates may be made of sheet metal having a thickness of 5 mm. The plates I0 are butt welded with a single butt strap on the lower side. When the bottom is finished the circular lowermost layer Il of the vertical sheet metal wall is welded to the bottom plate. The sheet metal of the vertical wall may also have a thickness of 5 mm. in the lowermost layer II and 4 mm. in the upper layers I2. The vertical joints between the wall plates II, I2 are butt welded with a butt strap oi' sheet metal, similarly as the bottom plate. The horizontal joints have overlapping welded joints, as shown at I3 (Fig. 5), the upper metal sheet being laid on the outside of the lower metal sheet and secured to it Vby means of a weld l on the inner side. To the vertical metal sheets and also to the edges of the bottom plate anchoring irons I4 are welded.

After the lowermost sheet II of the vertical wall has been mounted and welded to the bottom I I, a circular rai't is built on the bottom plate. 'I'he raft may consist of a deck 5I, for instance of wood, having a diameter slightly smaller than that of the tank. The deck may rest on floats l2 consisting, .for instance, of empty casks. Then water is filled into the lowermost part of the tank so that the water level is somewhat below the upper edge of the lowermost layer of metal sheets II. The outside of this layer is then carefully inspected to see if it is perfectly watertight. When water is filled into the tank, the raft is lifted to the upper edge of the lowermost layer. of

metal sheets Il. Now the temperature of the water within the tank is lowered by means of suitable cooling devices, for instance a refrigerator ll on the raft connected to a cooling pipe coil 54 submerged into the water, so that the temperature of the water will be lower than that o! the rock walls. For instance, the temperature of the water may be lowered C. below that of the rock. This causes the metal sheets II and the bottom plate IO to shrink and contract somewhat. Now water-tight concrete I5 is poured and tamped into the space between the rock I and the metal sheets Il so that also the pipes 3 and 5 and the anchoring irons I4 are encased within the concrete. In addition, vertical drain channels Il are made in the concrete. They may consist of tubes or rods, made, for instance of porous concrete. At the bottom these additional vertical drain channels I. are connected with the porous concrete block 1. During the pouring of the concrete and during its setting, the water in the tank is kept cooled. When the concrete has set and the refrigerator is put out of operation, the temperature raises a few degrees causing the sheet metal to expand somewhat so that it is pressed .against the concrete. Because it can be safely expected that the temperature of the liquid or iluid .to be stored in the tank can never have a temperature, which is more than some two degrees centigrade, below the temperature of the rock, the tank cannot contract to such a degree that its sheet metal will have a tendency to separate from the adjacent concrete I5. In other words, the metal sheets will never be subjected to, tensile stresses tending to draw them away from the concrete. On the contrary, the sheet metal of the vertical walls is permanently subjected to compressive strains tending to press the sheet metal against the concrete.

When theconcrete I5 has set, the second layer or course of the metal sheets of the vertical wall are mounted and welded to the lowermost course of sheets II. The raft floating in the tank is then used for carrying the workmen etc. during the mounting so that no scaffolding is necessary. After the second layer has been welded, the water level in the tank is raised again so that it can be controlled if the joints of the second layer are watertight. Then the material oi' the drain channels IB are laid in, the water is cooled and concrete vis poured and tamped between vthe rock and the second layer. Thus, the work'proceeds layer after layer, the metal sheets being successively mounted and welded. the water level raised, the tightness being tested and lconcrete being poured, until the upper edge of the tank is reached. Bere the sheet metal of the vertical wall is welded to a ring I1 for increasing the rigidity. All the while the water is kept at a lower temperature than that of the rock, and the mounting and the welding of the metal sheets. the pouring of the concrete etc. is made from the oating raft, whichis lifted successively, as the water level rises. To the upper ring I1 anchoring irons I8 are welded, before concrete is poured in up to the ring I1. To this ring also the metal sheets of the cupola or arched roof I9 are welded. 'I'he roof I9 is made of several metal sheets united by means of overlap welds.

To reduce the corrosion on the inside of the bottom plate, said plate is coated with oil-resistant synthetic resin lacquer, such as Bakelite lacquer, and the same coating is also applied on the lowermost portion of the vertical wall I I', say up to 20 cm. from the bottom plate. 'I'he upper side of the roof is coated with asphalt reinforced by means of fabric. In addition, the tank is mounted with pipes, valves and other devices in accordance with the conventional practice for self-supporting tanks in the open air. To the tank horizontal passages or tunnels 21, 28 lead at its top and its bottom. The lower passage 28 is closed by means of a strong wall 29 of concrete. Numeral 30 indicates a channel for collecting water. for draining purposes.

It is evident that the costs of erection oi' the tank according to this invention per cubic meter of ei'l'ective storage volume is considerably lower than for the self-supporting tanks standing free in underground cavities. because, in accordance with this invention, the tank walls may be very close to the rock and because a much thinner sheet metal may be used for building the tank. The costs of maintenance are also lower for a tank in accordance with the invention, because the otherwise very high maintenance cost for the outer side of the sheet metal is entirely eliminated. Since the concrete and thesheet metal form two sealing, fluid-tight layers, the security against leaking is double and risks are eliminated.

Should a leak occur both in the sheet metal and in the surrounding concrete, which is hardly possible, the liquid stored will ilow out into the draining channels i0 and then the liquid leaking out is found in the draining pipe 8. A leak can consequently be detected easily and early. Certainly, in the beginning the liquid only oozes out substantially drop by drop and it will take a considerable time, before a crack in the concrete will get such a size that any considerable leakage occurs. Consequently, there is ample time available for emptying the tank for repair. On the contrary, when a tank is standing free in an underground cavity, it must be immediately emptied to prevent a catastrophe in case of a leakage, and this obviously means that considerable reserve storage spaces, normally empty, must be provided. In contrast to this, no empty reserve storing tanks are necessary in accordance with this invention, in case of leaks.

Obviously stones cannot fall from the rock on the side walls of the tank, as may occur in plants having free-standing tanks in rock cavities. A

stone falling on the roof I9 has no sufcient path for gaining a great momentum and consequently is not dangerous. Reinforcing the ceiling of a rock cavity is also a comparatively simple work in accordance with this invention, because the reinforcements may easily be connected with the top of the concrete I5. On the contrary, in the plants heretofore known reinforcements are diiiicult and expensive.

When oil is stored in tanks standing free in a rock cavity, it is generally necessary to vent the cavity for reducing the rusting action. In such case the temperature of the liquid stored in the tank will substantially follow the temperature of the external air and will consequently vary much. But in the plant in accordance with this inention the liquid stored will have substantially the temperature of the underground rock, that is an approximately constant temperature of 6 to 8 C. all the year round. This means that for volatile liquids, such as gasoline, the losses due to evaporation are reduced or even substantially eliminated. Also the re risks are reduced or entirely eliminated.

What I claim is:

1. A method of building closed tanks for storing liquid fuel or other fluid in underground cavities, comprising, laying metal sheets on the bottom of the cavity, welding said sheets hermetically together to form a bottom plate, erecting vertical metal sheets on said bottom plate, welding said vertical metal sheets hermetically to said bottom plate and to each other to form a lowest structure, filling water into said structure up to its upper edge to determine that it is hermetically sealed, pouring concrete between said structure and the wall of the cavity, erecting an additional layer of vertical metal sheets on the top of said structure, welding said additional vertical metal sheets hermetically to each other and to said structure, raising the water level up to the upper edge of said additional layer to determine that the welded seams are hermetical, pouring concrete between said layer and the wall of said cavity, and adding additional layers of metal sheets vertically, until the tank is completed to the predetermined height.

2. A method of building tanks for storing fluids in underground cavities, comprising, laying a layer of metal sheets on the bottom of the cavity, welding said sheets together to form a bottom plate, inserting a raft on said bottom plate, erecting and welding vertical metal sheets in annular layers above each other at the edges of said bottom plate upwards to form a tank structure using said raft as a scaffold, lling water into said tank structure up to the edge of the layer just completed, to raise the raft and to test whether the last layer just completed is hermetically sealed, and pouring concrete between the layer thus filled and the wall of said cavity.

3. A method of building tanks for storing fluids in underground cavities, comprising, laying a layer of metal sheets on the bottom of the cavity,

welding said sheets together to form a bottom plate, erecting and welding vertical metal sheets in annular layers above each other at the edges of said bottom plate upwards to form a tank 5 structure, lling water into said tank structure substantially up to the upper edge of the layer just completed to test the hermetical sealing thereof, cooling the water to a temperature below that of the cavity walls, pouring concrete between the layer just completed and filled and the wall of said cavity, and keeping the water cooled during both the pouring and the setting of said concrete.

4. A method of building tanks for storing fluids l5 in cavities blasted in rock, comprising, laying a layer of metal sheets on the bottom of the cavity, welding said sheets together to form a bottom plate, drilling pipes into fissures of the rock wall proper, sealing the inner sides of the fissures by means of cement mortar around said pipes, connecting the pipes to collecting ducts inserted close by the rock wall, erecting and Welding vertical metal sheets in layers on the edges of said bottom plate upwards so that parts of said pipes become situated between the metal sheets and the rock Wall, pouring concrete between the metal sheets and the wall of the rock, and leaving said concrete to bind.

5. A method of building tanks for storing fluids in cavities blasted in rock, comprising, laying a layer of metal sheets on the bottom of the cavity, welding said sheets together to form a bottom plate, erecting vertical metal sheets at the edge of said bottom plate and in courses on each other, welding said vertical metal sheets to said bottom plate and to each other to form the vertical walls Y of a tank, inserting continuous rods of a porous material permeable to water between the rock wall and the metal sheets, connecting said rods with each other by means of other rods of porous material permeable to water, and pouring water-tight concrete between the metal sheets and the rock wall to embed said porous rods in said water-tight concrete to form a drainage system therein.

6. A method of building closed tanks for storing liquid fuel or other fluid in underground cavities, comprising, laying a bottom of metal sheets hermetically welded together on the bottom of said cavity, erecting metal sheets on said sheet metal bottom, welding said erected metal sheets to each other and to said sheet metal bottom to form an annular structure, filling water into said structure to determine that it is hermetically sealed, pouring concrete between said structure and the wall of said cavity, erecting yand welding other metal sheets in annular layers above each other on said structure, lling water into each layer, after it has been welded, to determine that said layers are hermetically sealed, pouring concrete between the wall of said cavity and said layer just we1ded,'and welding a cover of sheet metal to the top of the uppermost layer. o5 SVEN KLINGBERG. 

